The invention relates to a mechanical neck rest retraction device with a memory function.
In two-door vehicles, the rear-seats become accessible only by tilting forwards the backrest of the driver""s or front-passenger""s seat or the whole seat. If the neck rest is in a relatively elevated position a clash may occur between the neck rest and the roof or the sun visor of the vehicle. The same problematics appears in vehicles with a load pass-through function in which the rear backrest can be tilted forwards. Here, the neck rests may clash with the roof.
It is known as such to convert the tilting motion of the backrest or the whole seat into a retracting motion of the neck rest, which purpose normally is served by a pulling rope or Bowden cable, particularly a Bowden cable, which transforms the displacing force of the backrest into a pulling force on the neck rest rods. It further is known to automatically move out the neck rest again once the backrest is tilted back and the Bowden cable is relieved of its load. This is accomplished by means of a spring which engages the neck rest rods. Finally, it is also known to employ a so-called memory function here, i.e. to effect a positioning of the neck rest back to the same position from which it was retracted. Since the interacting components of such a retraction device naturally have a certain tolerance it is difficult in the known neck rest retraction devices to carry out the return travel to the original position in such a way that a locking action with the respective notch of the neck rest rod really is brought about.
It is the object of the invention to provide a mechanical neck rest retraction device in which the neck rest, after being retracted, surely is moved back to the original position of detent. Moreover, the neck rest is to be capable of manually being pulled upwards or being pushed in by actuating a control button like in conventional systems.
The object is attained by the following features of the present invention.
As is known as such, the invention provides a movably supported locking member which is designed to yieldingly be brought into engagement with one of several stop notches of a neck rest rod. In neck rest assemblies using no automatic retraction, the locking element mostly is disposed in the upper portion of the neck rest sleeve. In neck rest assemblies using an automatic retraction, the locking element normally is disposed within the seat or at the lower end of the neck rest sleeve because the interlocking needs to be separated from the automatic retraction device. In this case, the interlocking which is father below has to be actuated from the head of the neck rest sleeve via an appropriate reversal if the neck rest is intended to be pushed in by hand.
The invention further provides a bridge member which is connected to the lower end of the two neck rest rods. This also is included as such in the state of the art. The bridge member has movably supported therein a detent member which is biased by means of a first spring. According to the invention, an elongate actuator is provided which is adapted to be moved in parallel with the axis of the neck rest rods and which is engaged by a pulling rope, e.g. the actuating rope connected to the seat backrest in the shape of a Bowden cable or the like. The pulling rope, when actuated, will pull the actuator downwards against a second spring which biases the actuator upwards. The actuator is supported in a mounting disposed in the backrest which, therefore, is xe2x80x9cstationaryxe2x80x9d. Hence, if the term xe2x80x9cstationaryxe2x80x9d is referred to below this will mean xe2x80x9cfixed in the backrestxe2x80x9d.
The actuator has a series of detent recesses, which series extends in parallel with the neck rest rods or in parallel with the axis of the actuator. The gauge of the detent recesses is equal to the gauge of the stop notches in the neck rest rod. The previously mentioned detent member is opposed to the detent recesses, but gets into an engagement with one of the detent recesses, however, only under certain conditions which will be described below. Anyhow, the arrangement of the series of stop notches, on one hand, and the detent recesses, on the other, is such that if the neck rest rod is caught by an engagement of the locking element into one of the stop notches the detent member comes to lie between two adjoining detent notches.
The actuator interacts with a stationary guide, i.e. such that if the actuator is in an upper position the detent member is out of engagement with the actuator, but that the actuator is moved towards the detent member from a given displacement path onwards, which causes it to engage the next following detent recess.
Finally, the actuator has mounted thereon an unlocking member, which actuates said locking member for the release of the neck rest rod if the actuator is moved downwards. It is to be understood that the locking of the neck rest rod has to be cancelled if the neck rest is intended to be retracted.
It can be seen from the above description that if a pull is applied to the pulling rope the actuator is displaced, although a motion of the bridge member and a retraction of the neck rest do not take place yet initially. The result of the downward motion of the actuator is that the detent member in the bridge member engages the next following upper detent recess only after a certain displacement path of the actuator. Now, if the actuator is moved farther downwards it will also carry along the bridge member and, hence, the neck rest until this one comes to abut against the upper side of the backrest. If the backrest is tilted back again and, hence, the pulling rope is relieved from load the second spring will be able to displace the actuator and, thus, the neck rest to the top again, i.e. for a time until the guide brings the respective detent recess out of engagement with the detent member. This generates a certain excessive lift which surely guarantees that the locking element takes a position with respect to the originally occupied stop notch so that an efficient locking action takes place. The excessive lift is even enhanced by the fact that the detent recess, according to an aspect of the invention, is wider than the detent member so that in spite of the detent member getting caught in the detent recess it is not grasped by the actuator, during its downward motion, until the upper wall of the detent recess gets into engagement with the side of the detent member which is associated therewith.
According to an aspect of the invention, the actuator consists of two approximately parallel portions the first portion of which has the series of detent recesses and interacts with the guide and the second portion of which is connected to the pulling rope. Between the portions, an extension spring is disposed which transmits the motion of the second portion onto the first portion with the portions interacting via stops such that while the second portion is moving upwards the first portion is carried along. The unlocking member is connected to the second portion.
In this design, if the actuator moves downwards the bridge is thus actuated via the extension spring which is connected to the second portion which, in turn, is engaged by the pulling rope. Here, the function of the extension spring is to prevent any damage from occurring if the retraction mechanics is released with the neck rest pushed in. If the bridge member arrives early at the final stop the extension spring will be elongated and, hence, absorbs the force which is applied.
According to another aspect of the invention, the actuator may have a toothing with which a pivotally supported toothed segment interacts. The pulling rope engages the toothed segment. Thus, a gear ratio may be obtained for the path of the pulling rope. For example, the path of the pulling rope may be smaller than the path of displacement of the neck rest.
Various constructional options can be imagined for guiding the actuator in the backrest, e.g. in a holder plate or the like. According to the invention, one of them provides that the guide consists of a groove or slot that the one guide portion deflected from the detent member in the upper region has, but which, for the rest, is substantially straight and parallel to the longitudinal extension of the actuator. A follower portion is provided on the actuator, which engages the groove or slot. To prevent the actuator from unnecessarily being tilted two such grooves or slots preferably are provided, each with a cam follower of the actuator.
To reduce the length of the unlocking element, according to an aspect of the invention, a provision may be made to mount it on the actuator so as to be uncoupled by the actuator when it has travelled through a given path after the locking member is unlocked.
As a restoring spring for the actuator, it is preferred that a double-scroll spring be provided which displaces the actuator at a uniform force.